/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    SMOset.java
 *    Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.classifiers.functions.supportVector;

import java.io.Serializable;

/**
 * Stores a set of integer of a given size.
 * 
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision$
 */
public class SMOset implements Serializable {

    /** for serialization */
    private static final long serialVersionUID = -8364829283188675777L;

    /** The current number of elements in the set */
    private int m_number;

    /** The first element in the set */
    private int m_first;

    /** Indicators */
    private boolean[] m_indicators;

    /** The next element for each element */
    private int[] m_next;

    /** The previous element for each element */
    private int[] m_previous;

    /**
     * Creates a new set of the given size.
     */
    public SMOset(int size) {

        m_indicators = new boolean[size];
        m_next = new int[size];
        m_previous = new int[size];
        m_number = 0;
        m_first = -1;
    }

    /**
     * Checks whether an element is in the set.
     */
    public boolean contains(int index) {

        return m_indicators[index];
    }

    /**
     * Deletes an element from the set.
     */
    public void delete(int index) {

        if (m_indicators[index]) {
            if (m_first == index) {
                m_first = m_next[index];
            } else {
                m_next[m_previous[index]] = m_next[index];
            }
            if (m_next[index] != -1) {
                m_previous[m_next[index]] = m_previous[index];
            }
            m_indicators[index] = false;
            m_number--;
        }
    }

    /**
     * Inserts an element into the set.
     */
    public void insert(int index) {

        if (!m_indicators[index]) {
            if (m_number == 0) {
                m_first = index;
                m_next[index] = -1;
                m_previous[index] = -1;
            } else {
                m_previous[m_first] = index;
                m_next[index] = m_first;
                m_previous[index] = -1;
                m_first = index;
            }
            m_indicators[index] = true;
            m_number++;
        }
    }

    /**
     * Gets the next element in the set. -1 gets the first one.
     */
    public int getNext(int index) {

        if (index == -1) {
            return m_first;
        } else {
            return m_next[index];
        }
    }

    /**
     * Prints all the current elements in the set.
     */
    public void printElements() {

        for (int i = getNext(-1); i != -1; i = getNext(i)) {
            System.err.print(i + " ");
        }
        System.err.println();
        for (int i = 0; i < m_indicators.length; i++) {
            if (m_indicators[i]) {
                System.err.print(i + " ");
            }
        }
        System.err.println();
        System.err.println(m_number);
    }

    /**
     * Returns the number of elements in the set.
     */
    public int numElements() {

        return m_number;
    }

}
